54 



EXTERNAL CONFORMATION OF PLANTS. 



In the Characeoc, Monocotyledons, and Dicotyledons, the normal lateral branchlets spring 

 out of the axil of the leaf, /. e. above the leaves, in the acute angle which the leaf 

 forms with the stem (Figs.121,123). Usually only one is formed above the middle of the 



Fig. 121.— Longitudinal section of the apical region of 

 a shoot of Clematis apiifolia; s apex of the stem; bb 

 leaves ; gg the first traces of spiral vessels, bending out 

 uninterruptedly from the stem to the leaves. 



Fig. 122.— Bulb of Miiscari botrioides; one of the 

 lower bulb-scales is thrown back, in order to show the 



numerous buds standing side by side in its axil. 



insertion of the leaf, or 2-3 one above another; some- 

 times several are formed side by side above the middle 

 and right and left of it, as in the bulbs of Muscari (Fig. 

 122), and the flowers in the axils of the bracts of species 

 of Musa. Such branchlets are called axillary shoots; 

 in Monocotyledons and Dicotyledons the branching is, 

 with few (and usually doubtful) exceptions, axillary. 



(y) If we except some inflorescences in Phane- 

 rogams, the general rule that The normal Lateral 

 Shoots appear later than the youngest Leai^es deter- 

 mines the relationship in age ^. This is the case in 

 Characea^, Mosses (according to Leitgeb), Equisetaceae, 

 and the vegetative shoots and most inflorescences of 

 Phanerogams, as is shown in Figs. 106, 107, 109, 120, 

 121, 123. In Mosses it is clear that the youngest 

 branches stand at a greater distance from the apex 

 of the stem than the youngest leaves. In the other 

 groups named a different relationship would be possible ; but in these cases it may 

 also happen that the youngest lateral buds are almost always at a greater distance 

 from the apex than the youngest leaves ; or, in other words, the youngest leaves stand 

 between the youngest lateral shoot and the apex. If the position of the branchlet is 

 axillary, it would also be possible that when the formation of leaves ceases, the youngest 

 axillary shoot would be observed to stand above the youngest leaf ; but this would not 

 prove that it was in this case formed earlier. 



Fig. 123. — Apical region of a primary shoot 

 of Dictajn>t!is Fraxi>ie//a, seen from above; 

 J apex of the primary shoot; b b b the young 

 leaves ; A: /i: their axillary buds, the two young- 

 est leaves have not yet axillai-y buds. 



^ Hofmeister indeed maintains the contrary (AUgem. Morphologie, p. 911, 1868). Since that, 

 however, the Mosses have been shown by Leitgeb to be exceptions; and I constantly find in 

 vegetative shoots and many inflorescences of Phanerogams young leaves above the youngest 

 axillary buds. 



